In order to advance understanding of the operations underlying response determination, a central goal in the study of human performance, nine experiments on reaction time (RT) will be conducted over a period of three years which test a single-principle serial-operations model of the reaction process. In each operation a stimulus input is held to act on an excitable process to produce the succeeding excitable process, or finally the response itself. Split-information methodology will be used to verify and measure the durations of the operations. A variety of tasks will be used to generalize prior results indicating non-overlapping response-potentiation and actualization operations. Further, parallel procedures will be used to verify and measure the duration of the preparation-initialization operation, which has barely been studied. The primary split-information technique to be employed is the method of critical precues in which very brief precue-stimulus intervals (PSIs) are used. Seriality is demonstrated when the precue reduces RT by duration of PSI. The technique will also be used to test the model's contention of integral response potentiation as opposed to serial specification. Demonstration of the value of the new techniques will recommend them for analyzing tasks beyond the present concerns.